The research goals are to specify a series of models of economic and population interrelationships so that the extent of the dependency of population upon economic variables can be made more explicit and more subject to empirical verification. In proceeding in this way, it will be possible to make use of certain econometric and systems analysis tools to draw out the properties of the models. It will be possible, also, to estimate the quantitative structure of the models by use of cross-section (cross-country) and time series data. This will enable us to obtain estimates of the quantitative influence or effects of variables, including certain policy instruments, upon fertility variables (and in particular the net reproduction rate).